Lecitase® ultra as regioselective biocatalyst in the hydrolysis of fully protected carbohydrates Strong modulation by using different immobilization protocols

This paper shows that Lecitase Ultra is an enzyme preparation with a great interest as regioselective biocatalyst in the deprotection of 4 different peracetylated sugars: 1,2,3,4,6-penta-O-acetyl-beta-D-galactopyranose (1), 2-acetamido-2-deoxy-1,3,4,6-tetra-O-acetyl-beta-D-glucopyranose (4), 1,2,3,4,6-penta-O-acetyl-alpha-D-mannopyranose (7) and 2,3,4,6-tetra-O-acetyl-beta-D-galacto pyranosyl-(1 -> 4)-1,2,3,6-tetra-O-acetyl-beta-D-glucopyranoside (9). The enzyme properties (specificity, preference for the per-acetylated sugar and regio-selectivity) were strongly modulated by the immobilization conditions, for example the octyl-LECI preparation was 10 fold more active than the PEI-LECI preparation, while it was more than 40 fold less active against some other substrates. Very interestingly, these changes also affected the regioselectivity, depending on the preparation used it was possible to get free OH groups in anomeric position, position 6 or the mixture of both. Finally, the octyl-LECI preparation did not recognize the alpha-sugars, favouring the beta-isomers (in opposition to most commercial lipases or the other LECI preparations). This is potentially useful to obtain pure alpha-peracetylated monosaccharides from a mixture of anomers. (C) 2007 Elsevier B.V. All rights reserved.